The present invention relates to methods and devices for performing anastomosis. More particularly, the present invention relates to methods and devices for performing tissue-to-tissue or synthetic graft-to-tissue vascular anastomosis under either direct or transluminal access.
Anastomosis is the union or joinder of one hollow vessel or structure to another so that the interior of the vessels communicate with one another. There are generally two types of vascular anastomosis: end-to-end and end-to-side. In an end-to-end anastomosis, the severed end of a first vessel or an end of a synthetic graft is coupled, usually by suturing or stapling, to the severed end of a second vessel. In the context of a synthetic vascular graft, the ends and possibly intermediate portions of the graft may be secured to the wall of the vessel without removing a portion of the native vessel. In an end-to-side anastomosis, the severed end of a first vessel or an end of a synthetic graft is connected around an opening cut into the side of a second vessel.
Anastomoses are performed in a variety of anatomies, such as between airways, blood vessels, bowels, and urogenital lumens. The procedure for connecting blood vessels is referred to as vascular anastomosis. One of the best known surgical procedures utilizing vascular anastomosis is the coronary bypass. In the context of coronary artery disease, the flow of oxygenated blood to the myocardium of the heart is inhibited by a stenosis or obstruction in the coronary artery. This flow can be improved by providing a coronary artery bypass graft (xe2x80x9cCABGxe2x80x9d) between the aorta and a point in the coronary artery distal to the stenosis. Typically, a section of vein from the leg is removed and attached at one end to the aorta and at the other end to the coronary artery utilizing end-to-side anastomosis. Such grafts are known as saphenous coronary artery bypass grafts. Alternatively, synthetic grafts can be utilized to effect the bypass.
While the typical coronary bypass procedure favorably affects the incidence and severity of angina in patients with coronary artery disease, a variety of risks are associated with such procedures. Among them are mortality, myocardial infarction, postoperative bleeding, cerebrovascular accident, arrhythmias, wound or other infection, aortic dissection and limb ischemia. Furthermore, the vein grafts deteriorate over time, thereby resulting in the recurrence of angina, myocardial infarction and death. In addition, the costs of such procedures are relatively high and the patient recovery relatively long.
In an attempt to overcome such problems, a number of alternative approaches have been developed. For example, artery to artery bypass procedures have been utilized in which an arterial source of oxygenated blood-such as the left internal mammary artery (xe2x80x9cLIMAxe2x80x9d), right internal mammary artery (xe2x80x9cRIMAxe2x80x9d), or right internal thoracic artery (xe2x80x9cRITAxe2x80x9d)xe2x80x94is severed and anastomosed to the obstructed coronary artery distally to the stenosis or occlusion. More recently, other arteries have been used in such procedures, including the inferior epigastria arteries and gastroepiploic arteries. In general, artery to artery bypass procedures have demonstrated a better patency rate as compared with autologous vein or synthetic grafts.
While vascular anastomosis can be effective, and sometimes life-saving procedures, traditionally available techniques have been associated with a number of complications. For example, conventional techniques for performing vascular anastomosis generally require an extensive incision in the patient""s body. Such operations are traumatic to the patient, involve a lengthy recovery, and a relatively high risk of infection or other complications.
In the context of coronary bypass surgery, for example, the bypass graft or artery-to-artery procedure is traditionally performed using an open chest procedure. In particular, each procedure involves the necessity of a formal 20 to 25 cm incision in the chest of the patient, severing the sternum and cutting and peeling back various layers of tissue in order to give access to the heart and arterial sources. As a result, these operations typically require large numbers of sutures or staples to close the incision and 5 to 10 wire hooks to keep the severed sternum together. Furthermore, such procedures leave an unattractive scar and are painful to the patient. Most patients are out of work for a long period after such an operation and have restricted movement for several weeks. Such surgery often carries additional complications such as instability of the sternum, post-operative bleeding and mediastinal infection. Above all, open procedures are associated with long recuperation times.
Due to the risks attendant to such procedures, there has been a need to develop procedures which minimize invasion of the patient""s body tissue and resulting trauma. In this regard, limited open chest techniques have been developed in which the coronary bypass is carried out using an abdominal (subxyphoid) approach or, alternatively, a xe2x80x9cChamberlainxe2x80x9d incision (an approximately 8 cm incision at the sternocostal junction), thereby lessening the operating area and the associated complication rate. While the risks attendant to such procedures are generally lower than their open chest counterparts, there is still a need for a minimally invasive surgical technique. Nevertheless, each of these techniques is thoracotomic, requiring an incision to be made in the chest wall through which conventional surgical instruments are introduced to perform conventional coronary bypass surgery.
In order to reduce the risk of patient mortality, infection, and other complications associated with surgical techniques, it is advantageous and desirable to utilize endoscopic and thoracoscopic surgical techniques. Such procedures usually involve the use of surgical trocars to puncture the abdomen or chest, thereby facilitating access to a body cavity through the cannula and a relatively small opening in the patient""s body. Typically, such trocars have a diameter of about 3 mm to 15 mm. Surgical instruments and other devices such as fiber optic cameras can be inserted into the body cavity through the cannula. Advantageously, the use of trocars minimizes the trauma associated with many surgical procedures.
Another application involves the implantation and/or attachment of synthetic vascular grafts. Tubular vascular grafts comprising polytetrafluoroethylene (PTFE), Dacron, or other fabric materials may be implanted in a vessel to span a diseased or damaged site. In this application, the diseased portion of the vessel is merely isolated by directing blood flow through the graft. This may be accomplished by attaching the proximal end and distal end of the graft to the vessel wall proximally and distally of the diseased site. In some circumstances, portions of the graft in between the proximal and distal ends are preferably also attached to the vessel wall, to maintain patency throughout the graft. One application of such grafts is to treat abdominal aortic aneurysms, by implanting either a straight segment graft or a Y shaped xe2x80x9cbifurcationxe2x80x9d graft at the bifurcation of the lower abdominal aorta and the left and right iliac arteries.
When vascular anastomoses are performed, the goal is to achieve a sufficiently leak-proof connection between tubular structures. Typically, such connections in a CABG procedure are established using suturing techniques. Suturing of vascular structures, however, is a tedious and time consuming process. Furthermore, current suturing techniques are not possible using transluminal access, and are not readily adapted for endoscopic use, where the surgeon""s freedom of access and movement are limited. Thus, there is a need for an alternative to current suturing techniques that would expedite the anastomosis procedure, and that can be readily adapted for transluminal or endoscopic use.
Various stapling techniques are also known for providing anastomotic connections between organs, such as in intestinal and colorectal anastomosis. Due to the size of these devices, however, they are not easily adapted for use with vascular organs in general, and particularly not for transluminal or endoscopic techniques.
Surgical clips have also been developed, which are intended to facilitate the anastomosis of vascular structures. In this technique, the vascular tissues are approximated, partially everted, and then clipped by applying the arms of the surgical clip over the everted tissue and securing the clip so as to hold the tissue together without penetrating the interior wall of the vessel. Nevertheless, in order to properly utilize these clips, the tissues should be everted. A transluminal approach is thus not readily possible using this technique.
Thus, notwithstanding the various efforts in the prior art, there remains a need for methods and devices for performing vascular anastomoses which minimize the risk of infection, trauma, and other complications associated with conventional surgery, and, in particular, which can be utilized transluminally or in conjunction with an endoscopic technique for vascular anastomosis.
There is provided in accordance with one aspect of the present invention, a method of attaching a tubular graft to a vessel wall. The method comprises the steps of positioning a tubular graft within a vessel, and positioning a tissue anchor deployment catheter at a first position within the graft, the deployment catheter comprising a first plurality of tissue anchors. The anchors are thereafter advanced into the vessel wall, to secure the graft to the vessel wall. In one embodiment, the advancing the anchors step comprises advancing the anchors through the graft and into the vessel wall. Preferably, the advancing the anchors step comprises advancing at least four anchors into the vessel wall. In one embodiment, the positioning a graft step comprises positioning a tubular PTFE graft. Preferably, the method further comprises the step of advancing a catheter to a second position within the graft, and advancing a second plurality of anchors into the vessel wall. This may be accomplished using a second plurality of anchors, carried by the catheter.
In accordance with another aspect of the present invention, there is provided a method of attaching a first tubular structure to a second tubular structure in a patient. The method comprises the steps of identifying a first tubular structure in the patient, and positioning a second tubular structure in communication with the first tubular structure. An anchor deployment catheter is positioned within at least one of the first and second tubular structures. A plurality of tissue anchors are deployed from the catheter and through at least one of the first and second tubular structures, to attach the first tubular structure to the second tubular structure. The first tubular structure may be an artery or a vein, and the second tubular structure may be a graft. The graft may be autologous vessel tissue, a homograft, a xenograft, or a prosthetic tubular graft.
In accordance with a further aspect of the present invention, there is provided an anastomosis catheter. The anastomosis catheter comprises an elongate flexible body, having a proximal end and distal end. At least one tissue anchor support is provided on the body, moveable between an axial orientation and an inclined orientation. An anchor is movably carried by the anchor support. The anchor comprises a body, having at least one proximal engagement surface for resisting distal travel of the body through the tissue and at least one distal engagement surface for resisting proximal travel of the body through tissue.
In one embodiment, the tissue anchor support comprises a tube. The tube comprises a proximal section, a distal section and a hinge in-between the proximal section and the distal section. An actuator is preferably connected to the distal section, so that proximal retraction of the actuator with respect to the catheter body advances the anchor support from the axial position to the inclined position. Preferably, the catheter further comprises an introducer removably connected to the anchor for driving the anchor into the tissue. Preferably, the catheter comprises from about four anchor supports to about eight anchor supports.
In accordance with another aspect of the present invention, there is provided a method of tacking a tubular graft to a vessel wall. The method comprises the steps of identifying a tubular graft which has been previously positioned within a vessel. A tissue anchor deployment catheter is positioned within the graft, the deployment catheter comprising at least one tissue anchor. The anchor is thereafter advanced into the vessel wall, to secure the graft to the vessel wall.
Further features and advantages of the present invention will become apparent to those of skill in the art in view of the detailed description of preferred embodiments which follows, when considered together with the attached drawings and claims.